On most vehicles, the mounting of the license plates is accomplished by securing the license plate to a designated area by two bolts. The designated area is usually a flat surface on a part of the bumper formed to receive a license plate. However, on trailers such as boat trailers and utility trailers, the license plate is usually attached by bolts through holes in the top of the license plate to the lower frame or to a frame on a fender below the cruising light. Because trailers are low to the ground the license plate on some trailers is only a few inches from the ground. When the trailer is taken over rough ground, debris, obstructions, over ditches, potholes, etc, or when a boat is loaded or unloaded, the license plate strikes the ground or other obstacles, bending the license plate, or tearing the license plate from its mount.
A swinging license plate bracket is defined in U.S. Pat. No. 4,413,803, in which a special bracket is secured to a support frame by a hinge device. If the license plate strikes the ground, then the license plate can swing forward or back to prevent damaging a rigidly mounted license plate.
Various other mounting brackets have been designed that pivot at one edge of the license plate, but, for the most part, these designs are for tilting the license plate away from the mounting surface as in U.S. Pat. Nos. 3,702,510 and 3,389,486.